832 DR RAMSAY H. TRAQUAIR ON FOSSIL FISHES COLLECTED BY THE 



Genus LANARKIA, Traquair, 1898. 



Contour of head, body, tail, and fins as in TJielodus. Dermal armature consisting of 

 small, sharp, conical spines, hollow within and widely open below, without basal plate. 



The generic name is taken from the County of Lanark, in which the fish-bearing 

 Silurian beds are situated. 



Lanarkia Jiorrida, Traquair. 

 Plate III. figs. 1-6. 



1898. Lanarkia Jiorrida, Traq., in Director-General's Summary of Progress for 1897, p. 73. 



Specific Chaixicters. — Dermal spines mostly of one size, large for the size of the fish,, 

 and with expanded, somewhat trumpet-mouth shaped base. 



Description. — This is a small species, the length of which seldom exceeds two inches, 

 while the proportionally large size of its spines gives it a very decidedly prickly 

 appearance. 



Fig. 1, Plate III., represents a specimen from Birkenhead Burn, in which the form of 

 the head and pectoral region is more than usually undistorted, but the caudal fin is 

 absent. This deficiency is, however, supplied in fig. 2, in which it will, however, be 

 observed that the parts in front are pressed somewhat awry. Both figures are enlarged 

 by one-half. 



The spines are nearly equal in size all over the fish, save on the pectoral and caudal 

 fins, where they are smaller. On the pectoral fins there is also some appearance of 

 smaller spines intermixed with the larger ones. These appendages (figs. 3-6) have a 

 widely open trumpet-mouth-like base which passes, usually in an oblique manner 

 (fig. 3), up into a conical pointed shaft, which is externally finely striated longitudinally 

 (fig. 4). Fig. 5 represents a natural cast or impression of the interior of the base of one i 

 of those spines with the shaft broken off, and in fig. 3 a portion of the wall of the spine 

 has flaked away, showing the mould of the cavity within. Fig. 6 represents a group 

 consisting of three moulds of the interior and two impressions of the exterior of similar 

 spines. 



Position and Localities. — Downtonian Beds at Birkenhead Burn and Sefforholm. 



'OO' 



Lanarkia- spinosa, Traquair. 

 Plate III. figs. 7-12 ; Plate IV. figs. 1-2. 



1898. Lanarlia. epinosa, Traq., in Director-General's Summary oj Progress for 1897, p. 73. 



Specific Character. — Skin closely covered with minute pointed spines, among which 

 are scattered, in varying degrees of closeness, spines of a larger size, which are also conical 

 pointed and striated externally. 



